Ineffabilis Deus
The apostolic constitution in which Pius IX defined as revealed doctrine that the Virgin Mary was preserved from all stain of original sin from the first instant of her conception.
The letter reviews the liturgy, the Fathers and the acts of earlier popes, reports that the pope had consulted the bishops, and then gives the definition in the pope’s own name, “by the authority of Jesus Christ our Lord, of the Blessed Apostles Peter and Paul, and by our own”. It is dated at St Peter’s on 8 December 1854.
It is the document of record for the dogma of the Immaculate Conception. It is cited in the First Vatican Council because it was a doctrinal definition made by a pope without a council, sixteen years before the council defined when such definitions are infallible.
Cited in
- 8 December 1854, firm date
- 1869 to 1870, firm date